Anode tube for high voltage ionic valves



y 30, 1957 u. LAMM 2,801,357

ANODE TUBE FOR HIGH VOLTAGE IONIC VALVES Filed April 24. 1952 //1 venfor Uno Lam/11 United States Patent r 2,801,357 Y 'ANODE TUBE FOR HIGHVOLTAGE IONIC VALVES Uno Lamm, Ludvika, Sweden, assignor to AllmannaSvenska Elektriska Aktiebolaget, Vasteras, Sweden, a I corporation ofSweden Application April 24, 1952, Serial No. 284,026

Claims priority, application Sweden May 12, 1951 7 Claims. 01. 313-313In anode tubes of the type disclosed in Patent No. 2,446,600 withinsulating walls for high voltage ionic valves there are usuallyinserted between the anode and the cathode space several conductingbodies on which are impressed, during the inactive period of the valve,such potentials from a potentiometer resistor or the like as to make thevoltage distribution along the current path as uniform as possible, forthe purpose of preventing a back-arcing. A construction of theconducting bodies, in which each body has a number of channels ofsubstantial length (of the same order of magnitude as the width) and inwhich these channels lie opposite each other in the difierent bodies soas to form substantially straight through channels for the passage ofthe current, has for several reasons proved to be preferable to aconstruction, in which the bodies are substantially in the form of gridsthe ports of which may be displaced relatively to each other.

Experiments have however shown, that in using bodies having tubularchannels disturbances may arise in the form of a back current from thecathode to a body comparatively adjacent thereto. It is true that such aback current is limited by the potentiometer resistance, but it maystill initiate a total back-arcing or another disturbance. Ininvestigating the cause of this phenomenon the theory has been posedthat it may depend on the so-called hollow cathode effect, which impliesthat it is easier to initiate a glow discharge from a tubular cathodethan from a plane one, and which may be explained in such manner, thatelectrons movable in the cross direction will repeatedly rebound fromthe opposite walls of the tube and thereby obtain a total path ofmovement of such length, that the probability of provoking an ionisationby impact will be rather great also in a very thin atmosphere.

Starting from this theory, the object of the present invention is theelimination of the back current to conducting bodies having tubularchannels by such an arrangement, that the limiting walls of the freecross section of at least part of said channels contain at least twoportions of different potential. Free electrons which are repelled bythe body of the lower potential will then immediately be absorbed by thebody of the higher potential, whence a repeated rebounding of theelectrons is out of question. It has been found practically, that theabove construction has led to the desired result.

In order to achieve the said result it is advisable, that the bodieskept at difierent potentials have substantially the same extent in thelongitudinal direction of the tube, whereby all electrons repelled byone of the bodies have a chance to be absorbed by the other. It is alsodesirable that the bodies also in other respects form opposite sides ofthe tube wall, for instance either so that one semicylindrical part ofthe wall of each tube has one potential and theother semicylindricalpart another, or so that the channel is made annular in section with onepotential on its inner wall and another on its outer one.

Patented July 30, 195.7

As a rule, the main part of the body or disc containing the channels ismade in one-piece with a common potential, and a part separated from themain part and having another potential is arranged so as to form a wallpartially limiting the channel. The potential of the last-mentioned partmay for instance be equal to the potential of the main part of theadjacent disc, whereby the necessary number of leading-in conductors forimpressing the diflerent potentials need not be greater than for discshaving uniform potentials. Of course also another potential distributionmay be employed.

Two forms of the invention are illustrated in vertical sections in Figs.1 and 2 of the accompanying drawing, while Fig. 3 shows a cross-sectionon the broken line 33 in Fig. 2.

Each of the Figs. 1 and 2 shows three discs for potential distributionmounted in an anode tube 11 of insulating material, for instanceporcelain. The discs are shown as made from sheet metal, for instancesheet iron, and their inner parts are box-shaped, but they may as well,in a manner known per se, be of other material and substantially solid.Each box-shaped portion 12 has a circular row of channels 13 for thepassage of the current. In Fig. 1, the whole outer wall of each suchchannel 13 forms part of the same disc in the usul manner, but inaddition to this, there is a central cylinder 14 in each channel, makingthe free space in each channel of annular cross-section, and thiscentral cylinder is conductively connected to the main portion of theadjacent disc which also preferably supports it mechanically. In thisway, every portion of the free space in the channel will be limitedsidewise by two parts of different potentials, namely the outer wallhaving one potential and the central cylinder having a difierent one,equal to that of the main part of the adjacent disc, whereby practicallyany electron repelled from the surface having the lower potential isimmediately absorbed by the opposite surface having the higher potentialand thus no rebounding under repeated acceleration can take place.

Fig. 1 also shows an anode 17 and a potential resistor 18 forsuppressing dilferent potentials on the conducting bodies, and a controlgrid 20 and a cathode 19.

In Figs. 2 and 3, the dotted lines are intended to show the thickness ofthe material of the discs, and practically half of the outer wall ofeach channel 13 has one potential and the other half a different one.This is due to the fact that the central portion 16 of each disc has aposition which in height nearly coincides with that of the externalportion of the adjacent disc above. The boundary between the saidcentral and external portions substantially follows a cylindricalsurface through the center lines of the channels 13. In this manner,substantially half of the outer wall of each channel 13 will have apotential different from that of the other half, whereby the result willbe substantially the same as in the form according to Fig 1.

The lowermost disc preferably that lying nearest to the cathode-may as apart of different potential have one with essentially the potential ofthe cathode or of a grid 20 for ignition control or similar purpose,which may form an independent constructional element, thus not connectedto the main part of any disc.

If experience should prove that the perturbations intended to beeliminated by the present invention have not the same tendency to appearat all the voltage-distributing discs belonging to a series, but forinstance to appear only in the disc or discs next to one or both ends ofthe series, it may of course be sufficient to divide the discs intoportions of ditterent potentials only at the places where theperturbations show the greatest tendency to occur.

I claim as my invention: 1. Conducting .bodies for insertion; between.the anode and the, cathode space, inthigh voltage ionicvalves',l.=cornpr si g a t f n ul ama e ia .anumbe t id nducting i s supte y.S b;,,mai1S. qli mz pressing different potentials on adjacentconducting bodies, each of said conducting ,bodiesbeing provided with a.plurality of channels constituting .-dischar,ge paths, said channelsconsisting of wall portions from two adjacent conducti'ngbodies formingoppositelirniting walls in relation tQ'fiE discharge path of atileastsome of the channels.

2., Conducting bodies accordingtoclaim. 1,, in which the channel wallportions [frornithe two adjacent conduclingbodies have substantiallyequalextent in the direction of the discharge path through achannel, v

3. Conducting bodies acc0rding,to' claim 1, in which the parts are soconnected that a main channel wall portion has one potential and a minorwall portion has the same potential as the main wall portion of anadjacent conducting body.

' 4. Conducting bodies according to claim 1 in which the parts are soconnected that a main channel wall portion has one potential and anotherwall portion, forming substantially the half .of the circumference ofthe channel wall, which portion has the same potential as the main wallportion of an adjacent conducting body.

5. Conducting bodies according to claim '1, in which bodies consists ofa main channel wall portion of one potential, said portion forming theouter, circumferential wall of a discharge path, and another inner wallportion inside and co-axial with said last-mentioned wall portion, saidinner portion being mechanically connected with the adjacentconductingbody formingthemain wall portions of the channels through thesaid adjacent conducting body, the inner wall portions thus having thesame potential as that adjacentconducting body.

6. Conducting bodies according to claim 1, in which the parts are soconnected that a wall portion having a potential near that of thecathode forms one part of the condncting body lying nearest tothecathode.

7. Conducting bodies according to claim 1, in which the parts are sovconnected. that a wall portion having a potential near that of thecathode forms one part of the conducting body lying, nearest to thecathode and a portion. having thepotential of a control grid formsanother part of said conducting body.

References Cited in the file of this patent UNITED TDCFESv PATENTS

